One person is dead and at least 17 are wounded, including several children, in two mass shootings in major U.S. cities in 24 hours.

Late Saturday, a gunman opened fire on a street party in a Philadelphia neighborhood, injuring a toddler, two older children, and at least five adults. Two suspects are sought in connection with the attack.

"It appears that everybody was here for the picnic and everybody just ran... it looks like they just randomly fired down the street and just hit whoever was in their way," Philadelphia Police Lieutenant John Walker told NBC affiliate WCAU.

In a similar incident in the central city of Detroit Saturday, a gunman fatally shot a 20-year-old man and wounded nine other adults during a children's party on a basketball court.

The shootings follow the killing of nine African Americans at a historic black church in Charleston, South Carolina, by a suspected white supremacist last Wednesday.